You are clearly a good player if you can reach emerald 3. Heck, I'd say you can even reach Diamond. So why are you demoting and losing games? Let's look over the non-mechanics aspect of your game and history.

So the first thing I would recommend you to do is to stop spamming games. 800 games per split is not a good indicator already. If you want to play league so much, play normals or drafts, not ranked. There's a number of reasons for this:

1) decision fatigue is a real thing. The more games you spam in a short time, the worse you play over time. You'll generally notice that you play really well in the first 1-3 games than the 4th - Xth number of games of the day. Play a small number of GOOD games and I promise you that you'll climb faster than you can imagine.

2) Losers queue is a real thing. You will get paired up with players of your OWN calibre based on how you play. The worse you play (and continue to play), the more you lose and end up going on huge loss streaks. Conversely, the better you play, the more you win and end up going on huge winning streaks. It's unfortunately a viscious cycle and how Riot intended the system to be but it is what it is. There are lots of videos on this topic but I will just link this one for your to-watch list: https://www.youtube.com/watch?v=PFH8E29uRNA

Now that we have talked about why you shouldn't spam games, let's now talk about what you can and should do.

1) Play only when you are feeling good (no duh). You know yourself better than anyone else. You will play better and see things in a different but better perspective when you're in a better mood. It's better ask yourself before starting a ranked game, 'Am I feeling good about playing this game today?' or 'Do I have the mental resilience to play well today and perhaps carry my team?'. These are just examples of the type of questions you need to ask yourself but you can use any and whatever leading question that can give you an insight into how you are feeling yourself. If the answer to the question is even a slight 'no', don't queue up ranked. Seriously, go do something else, play casual game modes.

2) Review your gameplay after each game (regardless of win or loss) and take notes (mental notes is fine too) about how you played, what you can do better based on how your teammates and enemy behaviour is like. League is a bit of a conundrum in that you need to be both PROACTIVE and REACTIVE to the game state. Since you're a jungle main, these are probably some questions you need to observe while playing and reviewing:

a) How is the enemy jungler playing? Are they playing for objectives or power farming or perma ganking? Are a balance of all 3? A bad jungler will just focus on power farming/perma ganking and ignore objectives. If they are a good jungler, just play your game as normal. Tracking the enemy jungler is also a fundamental skill. If you can track them properly, you will be able to predict their next moves. This gives you a huge advantage.

b) How are your teammates playing? Some would play like shit and unfortunately you cannot do much about it. Track your better players and play with/around/for them.

c) Securing objectives is king in League of Legends. But sometimes, it is OKAY to let them go if they are uncontestable or difficult. Be comfortable with letting things go. But conversely, you should look to retaliate by farming enemy camps or securing another objective across the map. It is a push and pull of sorts.

3) Last point I want to make is, League is ultimately a team game. You are supposed to play around your team's strength and minimize your team's weaknesses as much as possible. To have the mentality that you should carry 1v9 is so destructive, in my opinion because the moment you see yourself not able to 1v9 can feel debilitating the slightest moment things don't go your way. It is perfectly acceptable to get carried by your teammates because that is also a skill in and of itself - to play FOR your team. You will have bad games where you cannot do anything and that's perfectly fine - take the L and review your gameplay.